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Search: Development[Title] AND genetic[Title] AND system[Title] AND Marinobacter[Title] AND adhaerens[Title] AND HP15[Title] AND involved[Title] AND marine[Title] AND aggregate[Title] AND formation[Title] AND interacting[Title] AND diatom[Title] AND cells[Title]

Development of a geneticsystem for MarinobacteradhaerensHP15involved in marineaggregateformation by interacting with diatomcells.

Jacobs University Bremen, School of Engineering and Science, 28759 Bremen, Germany.

Abstract

Diatom aggregation is substantial for organic carbon flux from the photic zone to deeper waters. Many heterotrophic bacteria ubiquitously found in diverse marine environments interact with marine algae and thus impact organic matter and energy cycling in the ocean. In particular, MarinobacteradhaerensHP15 induces aggregateformation while interacting with the diatom, Thalassiosira weissflogii. To study this effect at the molecular level, a genetic tool system was developed for strain HP15. The antibiotic susceptibility spectrum of this organism was determined and electroporation and conjugation protocols were established. Among various plasmids of different incompatibility groups, only two were shown to replicate in M. adhaerens. 1.4×10(-3) transconjugants per recipient were obtained for a broad-host-range vector. Electroporation efficiency corresponded to 1.1×10(5)CFU per μg of DNA. Transposon and gene-specific mutageneses were conducted for flagellum biosynthetic genes. Mutant phenotypes were confirmed by swimming assay and microscopy. Successful expression of two reporter genes in strain HP15 revealed useful tools for gene expression analyses, which will allow studying diverse bacteria-algae interactions at the molecular level and hence to gain a mechanistic understanding of micro-scale processes underlying ocean basin-scale processes. This study is the first report for the genetic manipulation of a Marinobacter species which specifically interacts with marine diatoms and serves as model to additionally analyze various previously reported Marinobacter-algae interactions in depth.